Adsorption properties of proteins at and near the air/water interface from IRRAS spectra of protein solutions

被引:0
作者
Marcel B. Meinders
Geertruida G. van den Bosch
Harmen H. de Jongh
机构
[1] Department of Structure and Functionality,
[2] Wageningen Centre for Food Sciences,undefined
[3] Diedenweg 20,undefined
[4] Wageningen,undefined
[5] The Netherlands,undefined
[6] Department of Food Structure and Technology,undefined
[7] ATO Agrotechnological Research Institute,undefined
[8] Bornsesteeg 59,undefined
[9] Wageningen,undefined
[10] The Netherlands,undefined
[11] Department of Food Chemistry,undefined
[12] Wageningen University,undefined
[13] Bomenweg 2,undefined
[14] Wageningen,undefined
[15] The Netherlands,undefined
来源
European Biophysics Journal | 2001年 / 30卷
关键词
Infrared reflection absorption spectroscopy β-Casein Protein solutions Air/water interface Spectral simulation;
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摘要
A detailed study is performed using infrared reflection absorption spectroscopy (IRRAS) to characterize the molecular behaviour of proteins at and near the air/water interface of protein solutions. IRRAS spectra of β-casein solutions in H2O and D2O show spectral shifts and derivative-like features not commonly observed in monomolecular layer systems. They can be fully understood using optical theory. Fair agreement between experimental and simulated IRRAS spectra over a broad spectral range (4000–1000 cm–1) is obtained using a stratified layer model. An attenuated total reflection and transmission spectrum is used to represent the protein extinction coefficient in H2O and D2O, respectively. It is shown that the derivative-like features observed result from the reflective properties of the proteins themselves. Furthermore, both concentration and film thickness could be fitted. At high protein concentrations (100 mg/mL) the spectrum is that of a single homogeneous protein solution. At 0.1 mg/mL, β-casein is accumulated at the surface in a thin layer of approximately 10 nm thickness, with a concentration about 2500 times higher than in the sub-phase. At an initial concentration of 10 mg/mL, the concentration in the surface layer is about 15 times higher than in the sub-phase, while the thickness is about 30 nm.
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页码:256 / 267
页数:11
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